Roller cone drill bits with optimized cutting zones, load zones, stress zones and wear zones for increased drilling life and methods

Abstract

Roller cone drill bits may be formed with cutting elements and cutting structures optimized to increase downhole drilling life of an associated drill bit. The cutting zone, load zone and wear zone of each cutting element may be analyzed by finely meshing each cutting element into many small segments. The number of contacts between each meshed segment and portions of a downhole formation may be determined during discrete drilling time periods. A distribution of sliding velocity for each segment relative to portions of the downhole formation may also be determined during the discrete drilling time periods. Force profiles for each cutting zone may be used to determine associated loading zones. A wear profile for each cutting element may be estimated by combining the associated force profile with the associated distribution of sliding velocity.

1. A roller cone drill bit comprising:
 a bit body having at least one support arm extending therefrom; 
 a respective cone assembly rotatably mounted on each support arm for engagement with a subterranean formation to form a wellbore; 
 each cone assembly having a respective axis of rotation extending from the associated support arm; 
 each cone assembly having at least two rows of cutting elements; 
 each cutting element including a hardfacing material having a thickness, the thickness and a location of the hardfacing material on each respective cutting element designed based on a stress zone and a wear zone determined by simulated interaction of the respective cutting element and portions of the subterranean formation; and 
 each cutting element designed with a respective cutting zone and a respective loading zone at optimum locations for the respective cutting element based on the location of the respective cutting element on the respective cone assembly and simulated interaction of the respective cutting element and portions of the subterranean formation. 
 
     
     
       2. The drill bit of  claim 1  wherein the cutting elements comprise a plurality of inserts attached to the cone assemblies. 
     
     
       3. The drill bit of  claim 1  wherein the cutting elements comprises a plurality of milled teeth formed as part of the cone assemblies. 
     
     
       4. A roller cone drill bit comprising:
 a bit body having three support arms extending therefrom; 
 a respective cone assembly rotatably mounted on each support arm for drilling engagement with a subterranean formation to form a wellbore; 
 each cone assembly having respective rows of cutting elements; 
 each cutting element including a hardfacing material having a thickness, the thickness and a location of the hardfacing material on each respective cutting element designed based on a stress zone and a wear zone determined by simulated interaction of the respective cutting element and portions of the subterranean formation; and 
 each cutting element designed with a respective cutting zone and a respective loading zone at optimum locations on the respective cutting element based on the location of the respective row of the cutting element and simulated interaction of the drill bit and respective cutting element with portions of the subterranean formation. 
 
     
     
       5. The drill bit of  claim 4  wherein the cutting elements comprise a plurality of inserts attached to the cone assemblies. 
     
     
       6. The drill bit of  claim 4  wherein the cutting elements comprises a plurality of milled teeth formed as part of the cone assemblies. 
     
     
       7. The drill bit of  claim 4  wherein each cutting element comprises a respective wear zone to optimize drilling life of the drill bit. 
     
     
       8. The drill bit of  claim 4  wherein each cutting element comprises a respective stress zone to optimize drilling life of the drill bit. 
     
     
       9. The drill bit of  claim 4  further comprising the respective cutting zone of each cutting element designed to optimize rate of penetration of the drill bit through the subterranean formation. 
     
     
       10. The drill bit of  claim 4  further comprising the respective loading zone of each cutting element designed to optimize rate of penetration of the drill bit through the subterranean formation. 
     
     
       11. The drill bit of  claim 4  further comprising the respective cutting zone of each cutting element designed to optimize force balance of the drill bit as it proceeds through the subterranean formation. 
     
     
       12. The drill bit of  claim 4  further comprising the respective loading zone of each cutting element designed to optimize force balance of the drill bit as it proceeds through the subterranean formation. 
     
     
       13. The drill bit of  claim 4  further comprising the respective cutting zone of each cutting element designed to optimize work balance of the drill bit as it proceeds through the subterranean formation. 
     
     
       14. The drill bit of  claim 4  further comprising the respective loading zone of each cutting element designed to optimize work balance of the drill bit as it proceeds through the subterranean formation. 
     
     
       15. A roller cone drill bit comprising:
 a bit body having at least one support arm extending therefrom; 
 a respective cone assembly rotatably mounted on each support arm for engagement with a subterranean formation to form a wellbore; 
 each cone assembly having a respective axis of rotation extending from the associated support arm; 
 each cone assembly having at least two rows of cutting elements; 
 each cutting element including a hardfacing material having a thickness, the thickness and a location of the hardfacing material on each respective cutting element designed based on a stress zone and a wear zone determined by simulated interaction of the respective cutting element and portions of the subterranean formation; and 
 each cutting element designed with a respective cutting zone and a respective loading zone at optimum locations for the respective cutting element based at least in part on the respective row of the cutting element. 
 
     
     
       16. The drill bit of  claim 15  wherein the simulated interaction of the respective cutting element and portions of the subterranean formation includes using a three dimensional mesh representation of each cutting element. 
     
     
       17. The drill bit of  claim 15  wherein each cutting element comprises a respective wear zone to optimize drilling life of the bit. 
     
     
       18. The drill bit of  claim 15  wherein each cutting element comprises a respective stress zone to optimize drilling life of the drill bit. 
     
     
       19. The drill bit of  claim 15  further comprising the respective cutting zone of each cutting element designed to optimize rate of penetration of the drill bit through the subterranean formation. 
     
     
       20. The drill bit of  claim 15  further comprising the respective loading zone of each cutting element designed to optimize rate of penetration of the drill bit through the subterranean formation.